A bond magnet is manufactured by molding a compound prepared by mixing and kneading magnetic alloy powders of desired compositions with resins, a flame retardant and so on, into various shapes by means of injection molding, compression molding and extrusion molding, so that thin and complicated shapes can be easily manufactured and uniform characteristics obtained without cracks and chips. Such magnets are widely used in magnetic circuits of electronic components, in audio equipment, OA equipment and the like.
Conventionally, a ferrite magnet powder and a rare earth magnet powder are generally used as the magnet powders for the bond magnet, and alnico magnet alloy powder is also used in a focusing magnet for focusing electronic beams and in color adjusting convergence in picture tube in television or display Braun tubes, because of its (1) superative temperature characteristics, (2) a higher saturated magnetic flux density than the ferrite magnet powder, and superior oxidation resistance and weatherproof as compared with the rare earth magnet powder. Such powders are furthermore low in cost.
As the alnico magnet, alnico 8 having a coercive force of 1000 Oe or more and alnico 5 having a coercive force of about 500 to 700 Oe are well known, both having a low temperature change of magnet characteristics of 0.05%/.degree.C. or less.
The inventor has previously proposed bond magnets of alnico 5 and alnico 8 (Japanese Patent Application Laid Open No. Hei 4-239103), and an alnico bond magnet is also disclosed in the Japanese Patent Application Laid Open Nos. Hei 3-239306 and Hei 3-259502.
However, since the Alnico type magnet alloys consisting of alnico 5 and alnico 8 all contain a large amount of Co, i.e., about 25% to 40%, there was the possibility of high product cost and uncertainty in supply of raw materials.
Also, though fire resistance is required a bond magnet used in domestic appliances and in OA equipment, some products using a bromic flame retardant have the possibility of producing dioxine having a toxicity at the time of combustion, thus the regulation of its use is being studied in U.S.A. and Europe.
It is an object of the present invention to provide alloy powders for bond magnet which do not contain cobalt, which is scarce in resources, and is composed mainly of Fe-Ni-Al-Cu having good temperature characteristics, and to provide a bond magnet containing a flame retardant which is safe to dispose and at the time of combustion such as a fire.